This invention relates to audio signal processing and more particularly to incorporating different spatial characteristics into multiple independent audio signals.
Context switching in telephony applications traditionally comprises multiple telephone lines that are output to a desktop telephone handset. The context switch allows a phone user to selectively listen to one active telephone line and put any number of additional active telephone lines in a "hold" state. Thus, the telephony applications, such as voice mail, are presented to a user in an audibly mutually exclusive fashion that prohibits simultaneous presentation of other auditory inputs to the phone user.
Conferencing features sum together incoming line appearances to an end user. However, the conferencing feature also allows each line appearance to monitor the sum of all other conferenced appearances, which may not be desired. The conferencing features traditionally offered in telephony products are monaural and mix the incoming sound sources into a single point source. A point source is defined as a spatial location where one or more sound sources are audibly perceived as coming from. For example, when listening to an orchestra, the different musical instruments are each audibly perceived as coming from different point sources. Conversely, when listening to a telephone conference call, the voices on the telephone lines are all perceived as coming from a common point source.
Since the sound sources in a telephone conference call appear to all come from a single point source, a listener has difficulty differentiating between the incoming sources. Techniques which employ stereo presentation for conference calling do not allow the user to move incoming sound sources into perceptibly different foreground and background sources. Since each sound source appears to come from the same location, audio intelligibility for one specific sound source of interest is decreased when multiple sound sources are broadcast at the same time.
Accordingly, a need remains for an audio context switching system that improves the ability to monitor and differentiate multiple sound sources at the same time.